Core (Au)-shell (Ag) structure nitrogen dots for the recognition of nitroaniline isomers by surface-enhanced Raman scattering

In this work, we report a facile synthesis method for NDs-Au@AgNPs surface-enhanced Raman scattering (SERS) substrate using Au seeds prepared by nitrogen-rich quantum dots (NDs). As a new member of quantum-dots family, NDs are rich in nitrogen and oxygen-containing functional groups and therefore can be used as an efficient reducing and stabilizing agent for the synthesis of AuNPs. The NDs-Au@AgNPs with core-shell structures was synthesized by seed-mediated growth method in presence of NDs-AuNPs seeds and exhibited high SERS activity with a high SERS enhancement factor of 10⁷. The NDs-Au@AgNPs SERS substrate was effectively used for the recognition and detection of isomers of meta, ortho and para nitroanilines, while commercial SERS substrate cannot. In addition, the possible adsorption behavior was further studied, which is of great significance for the related work about differentiation of isomers and the mechanism of SERS enhancement.